The adopted values of MB00 from the various
calibration methods are
listed together in Table 5. Not one of the
individual values can be
regarded to be free of the possibility of serious external error, but
the mutual consistency of these independent estimates is encouraging.
Assigning double weight to the absolute magnitudes obtained from the
Virgo cluster SNe Ia and from the radioactivity
method, and disregarding
the thermal emission estimate on the grounds that the external error is
unknown but may be large, we obtain as the best current estimate
MB00 = - 19.6 ± 0.2.